The present invention relates generally to N,N,N′-trimethyl-bis-(aminoethyl)ether and derivatives thereof, compositions employing such compounds, polyurethane gel and foam formulations, and methods of making polyurethane gels and foams.
Polyurethane foams are widely known and used in automotive, housing and other industries. Such foams are produced by reacting a polyisocyanate with a polyol in the presence of various additives. One such additive is a chlorofluorocarbon (CFC) blowing agent which vaporizes as a result of the reaction exotherm causing the polymerizing mass to form a foam. The discovery that CFC's deplete ozone in the stratosphere has resulted in mandates diminishing CFC use. Production of water-blown foams, in which blowing is performed with CO2 generated by the reaction of water with the polyisocyanate, has therefore become increasingly important. Certain tertiary amine catalysts have been used in the production of polyurethanes and polyurethane foams. Such tertiary amine catalysts can be used to accelerate both blowing (reaction of water with polyisocyante to generate CO2) and gelling (reaction of polyol with isocyanate).
The ability of the tertiary amine catalyst to selectively promote either blowing or gelling is an important consideration in selecting a catalyst for the production of particular polyurethane foam. If a catalyst promotes the blowing reaction too selectively, much of the CO2 will evolve before sufficient reaction of isocyanate with polyol has occurred. As a result, the CO2 will bubble out of the formulation, resulting in a collapse of the polymerization mass yielding foam of poor quality. In contrast, if a catalyst too strongly promotes the gelling reaction, a substantial portion of the CO2 will evolve after a significant degree of polymerization has occurred. Again, poor quality foams are produced. These foams are generally characterized by high density, broken or poorly defined cells, or other undesirable features. Thus, a balance is needed between reaction of the isocyanate and the polyol (gelling) and the reaction of the isocyanate with water (blowing) in order to produce a polyurethane foam in which the cells are substantially uniform and the foam has suitable properties depending on the anticipated application; for example, rigid foams, semi-rigid foams, and flexible foams.
Tertiary amine catalysts generally are malodorous and offensive and many have high volatility due to their low molecular weight. The release of tertiary amines during foam processing may present safety and toxicity problems, and the release of residual amines from customer products is generally undesirable.
Thus, there exists a need for a catalyst composition that is thermally stable during urethane processing and can produce foams substantially free of volatile amines and/or amine odors. Catalysts containing functionalities capable of reacting with isocyanate are desirable because they can be immobilized in the polyurethane matrix to yield products substantially free of amine emissions. In addition to the isocyanate reactive site, a high molecular weight moiety that imparts low vapor pressure to the amine catalysts is advantageous. Further, it is beneficial for the catalyst composition to promote a balance between the blowing (water-isocyanate) and gelling (polyol-isocyanate) reactions in order to produce foams of good quality and acceptable physical properties. Accordingly, it is to these ends that the present invention is directed.